Refrigerator



Patented Oct. 6, 1936 UNITED STATES PATENT. OFFICE REFRIGERATOR v JohnLithgow, Chicago, Ill.

Application'February 17, 1932, Serial No. 593,506

6 Claims. (01. 2-915) The invention relates generally to refrigeratorsand more particularly to refrigerators adapted to employ as arefrigerant a substance having a temperature lower than that of waterice.

An object of the invention is to provide a refrigerator of new andimproved construction and arrangement of parts for using with maximumefliciency the entire refrigerating effect of substances having atemperature lower than 32 Fahrenheit. Solid carbon-dioxide, preferablyin the form of compressed snow and known commercially as dry ice, isgiven as an example of such a substance.

Another object of the invention is to provide a refrigerator for thistype of refrigerating substance which embodies a substance containercapable of being constructed either as an integral part of a householdrefrigerator, or as an attachment for existing household refrigeratorsand 20 wherein the structure of the container and its relationship tothe refrigerator proper maintains a constant predetermined refrigeratingtemperature within the refrigerator regardless of the quantity ofsubstance in the container. 25 A further object of the invention residesin the provision of a novel means for utilizing the waste gas from arefrigerator employing solid carbondioxide as a refrigerant to carbonatebeverages.

Other objects and advantages will become apparent in the followingdescription and from the accompanying drawing, in which:

Figure l is a front elevation on a reduced scale of a householdrefrigerator embodying the features of the invention.

35 Fig. 2 is a vertical section through the ice compartment as indicatedby the line 2-2 in Fig. 1. Fig. 3 is a transverse section through theice compartment taken along the line 3--3 in Fig. 2.

Fig. 4 is a front elevation of the ice compartment of a refrigeratorshowing a modification of the invention.

Fig. 5 is a fragmentary side view of a refrigerator illustrating anothermodification. I While the invention is. susceptible of variousmodifications and alternative constructions, I have shown in the drawingand .;will herein describe in detail the preferred embodiment, but it isto be understood that I do not thereby intend to 50 limit the inventionto the specific form disclosed,

but intend to cover all modifications and alternative constructionsfalling within the spirit and scope of the invention as expressed in theappended claims.

55 In the followingdescription, the .use of dry ice or solidcarbon-dioxide will be described in connection with a householdrefrigerator as being illustrative of the use of a refrigerant which hasa temperature of less than 32 Fahrenheit.

Referring to Fig. l, the numeral l designates generally a'householdrefrigerator having doors I I and [2 opening into'food and refrigerantcom partments respectively. This construction is substantially the sameas that which is at present conventional in water ice refrigerators. Insuch constructions, it is customary to arrange the refrigerator interiorso that by convection, heated air therein flows from the top of the foodcompartment into the top of the ice compartment, downwardly over andpast all sides of the refrigerant to become cooled, out of the icecompartment into the. food compartment, and thence upwardly in the foodcompartment as the gas becomes heated. Obviously, the amount of heatabsorbed is in direct proportion to the surface area of the refrigerantexposed to air circulation. Consequently, there is, in any water icerefrigerator, an undesirable and unavoidable wide variation in internaltemperatures as a large volume of water ice melts away to nothing.

An important feature of the present invention resides in the provisionof means for eliminating this temperature variation in householdrefrigerators. To this end, a dry ice container I3 is provided forinstallation in the ice compartment of a household refrigerator, saidcontainer being in the form of a box l4 having a closure I5 permittingof access thereinto. The container, when closed, is gas tight. In thepresent construction the container construction embodies inner walls I6,spaced outer walls ll, both being of a good heat-conducting material,and a separating layer [8 of heat insulating material therebetween. Theclosure [5 is of similar construction.

The container is supported in spaced relation to the bottom wall of theice compartment by suitable members l9. It will be evident that therefrigerator may be manufactured with the container as. an integral partthereof or that the containermay be produced as an attachment unit forincorporation in existing refrigerators. Moreover, it is possible, aswill become apparent, to construct and arrange the assembly so that thecontainer is readily detachable from the refrigerator whereby .arefrigerator is produced which is convertible for consumption of dry iceor water me.

As has been mentioned, the-inner and outer container walls 16, H areheat conducting.

When, therefore, a quantity of dry ice is placed in the container, theconductivity of the walls equalizes the temperature and insures that thetemperature over the external surface of the container is uniform. Forthe same reason, the temperature remains constant regardless of thequantity of dry ice therein. The temperature within the container isapproximately minus 110 Fahrenheit when the dry ice is surrounded bypure carbon-dioxide.

Advantage is taken of the fact that carbondioxide gas is heavier thanair to maintain an atmosphere of pure carbon-dioxide gas about the dryice by providing a small duct or conduit 20 from the top of thecontainer. rounding gas further insures that the temperature will remainconstant and uniform. The conduit 20 communicates with the interior ofthe container through an extension 2| and discharges to atmosphereexternally of therefriger- 'ator through a similar extension 22 mountedin a side wall. Detachable glands 23 of a conventional type connect theconduit and extensions. The extensions are formed of a suitable heatinsulating material to prevent heat transfer from the exterior to theinterior of the refrigerator through the extension 22 and thence to theinterior of the container through the extension 2l.' If one or the otherof the glands 23 is disconnected, the container may be readily removedfrom the ice compartment to adapt the refrigerator for Water ice.

In mounting the container within the ice compartment, the most eflicientrefrigeration or heat transfer is obtained when the walls of thecontainer are all spaced from the opposing walls of the compartment, asshown in Figs. 2 and 3, whereby free circulation of air about thecontainer is obtained. Since the external area and temperature of thecontainer is constant, the quantity of heat energy taken up as the airwithin the refrigerator circulates will also be constant.

It will be evident that the reduced temperature which might be obtainedby the use of dry ice in a small refrigerator would be much too low forordinary refrigeration purposes. An important feature of the inventionis a novel arrangement whereby a predetermined temperature within therefrigerator is positively and efficiently maintained without mechanicalcontrol. The customary construction of a household refrigerator includesa layer of insulation Ill (Fig. 2 as a part of the outer wall structure.This insulation does not entirely prevent the transfer of heat energythrough the walls of the refrigerator and the effect of the insulationis, therefore, to determine the mean refrigerating temperature withinthe refrigerator. In my refrigerator, the total heat transfer throughthe container walls l6, l1 and insulation I8 is, as nearly as ispractically possible, arranged to be the same'as, or to balance, thetotal heat transfer through the walls of the refrigerator. For apractical example, it is presumed that the insulating effect of therefrigerator walls maintains a mean internal temperature of 40Fahrenheit. The quantity of heat energy which is absorbed through theinsulated walls of the refrigerator to produce this temperature may bereadily calculated. The container walls are, therefore, insulated topermit the absorption therethrough of the same quantity of heat energy.As a result, the heat transfer or loss of therefrigerator is balanced bythe heat loss This surof the container and the temperature within therefrigerator will be maintained at the proper point.

The entire specific heat of the gas is utilized in the present device upto or slightly beyond the internal temperature of the refrigerator byforming a number of convolutions, indicated generally at 24 (Fig. 3), inthe conduit 20 and. by locating the conduit adjacent the top surface ofthe container where it is in the path of the air of heighesttemperature. Consequently, the specific heat of the exhaustcarbon-dioxide gas is utilized to absorb the maximum of heat energybefore it is discharged.

In Fig. 4 is shown a slightly modified form of the invention wherein adry-ice container 25 'is built into the ice compartment as a permanentpart of the refrigerator. In this construction, the open face of thecontainer is substantially coincident with the opening in the icecompartment, the container walls which define said open face beingsecured to the refrigerator frame. A single closure 26 for the icecompartment opening will, therefore, close the container and should, ofcourse, seal the container against gas leakage. This constructioneliminates one closure in the double closure construction but, ofcourse, only exposes five sides of the container to air circulation. Thelatter objection is not serious, however, since the insulation of thecontainer may be arranged to compensate for the elimination of the sixthside. The closure 26 should be very well insulated against heat transferand for this reason the inner surface thereof is preferably of aninsulating material such as a sheet 21 of fibrous material.

If desired, the present invention may be readily adapted to freeze icecubes. In one arrangement for this purpose the container is providedwith a horizontal partition 28 (Fig. 4) having opposed L-shaped brackets29 thereon for engaging the flanges 30 customarily provided on an icecube tray or pan 3|. Water in the pan will be sub jected to theexceedingly low temperature within the container and may, therefore, befrozen in a very short time.

With reference to Fig. 5, one form of means for utilizing the otherwisewasted -'calrbon--dioxide gas for carbonating beverage is illustrated.Thus, a closed carbonating tank 32 or the like, having a filling opening33 and an outlet faucet 34, is supported by suitable brackets 35 on oneside of the refrigerator. The conduit extension 22 has a relief valve 36of well known construction attached thereto and a duct 31 connects theextension with the tank. If the relief Valve 36 is adjusted to open at apressure greater than the usual carbonating pressure (generally aboutten pounds per square inch) the gas, until that pressure is reached,will be by-passed to the liquid in the tank to carbonate it. All gas notrequired for carbonation purposes will, of course, be exhausted toatmosphere through the relief valve 36. Preferably, the flow of gas tothe tank 32 is controlled by a suitable valve 38' interposed in the duct31.

It will be evident from the foregoing that a novel refrigerator has beenprovided which is simple in construction and is efficient in operation.Dry-ice or a similar low temperature refrigerant is efficiently utilizedto maintain a definite refrigerating temperature within the refrigeratorwithout mechanical control means which are apt to fail because of theextremely low temperatures to which they are necessarily subjected.Moreover, the present device is advantageous in that no waste gas canescape into the food compartment whereby the injurious effect of the gason the food stuffs therein is not encountered.

I claim as my invention:

1. A refrigerator comprising, in combination, an insulated box-likestructure having internal food and refrigerant receiving compartments,an insulated container for solid carbon-dioxide mounted in therefrigerant compartment in spaced relation to the walls of thecompartment to permit air to flow about the container, said containerstructure including spaced walls of heat conducting material and heatinsulating material separating the walls, and a conduit for conveyingwaste gas from the upper part of the container interior to atmosphere,said container walls having a heat transferring capacity substantiallyequal to the heat transferring capacity of the Walls of the box-likestructure.

2. In a refrigerator, the combination of a closed container for solidcarbon-dioxide as a refrigerant, means for mounting said container in arefrigerator, and a waste gas conduit communicating with the interior ofthe container, said conduit having an end of material which is anonconductor of heat extending through a wall of the container tominimize heat transfer by the conduit.

3. A refrigerator comprising, in combination, an insulated refrigeratorstructure embodying substantial interior compartment space, an insulatedcontainer for a subliming refrigerant and removably mounted in saidstructure, means for supporting said container in spaced relation to thewalls of the compartment to permit air flow thereabout, means forgaining access to the interior of said container for refilling the samewith refrigerant, and a conduit for conveying waste gas from theinterior of said container to the exterior of said structure, saidcontainer including spaced walls of a material substantiallyimpenetrable by gas and separated by heat insulating material forretarding the passage of heat into said container, said container wallshaving a heat transfer capacity substantially equal to the heat transfercapacity of the walls of the refrigerator structure whereby the heattransfer through said structure will be balanced by heat transferthrough said container and sublimation of said refrigerant.

4. In a refrigerator adapted for the use of solid carbon-dioxide as arefrigerating medium, the combination of a refrigeration structureadapted for convection circulation of enclosed air and having a sealedcontainer therein for solid carbon dioxide, said container beingarranged for air circulation in contact therewith so as to transfer heatto said container to effect sublimationof said solid carbon dioxide andcooling of the air, a gas conduit extending from the container to theexterior of said structure for conducting waste gas from the container,a carbonating tank for liquors mounted on said structure and connectedwith said conduit, and a relief valve interposed in said conduit betweensaid container and said tank and arranged to exhaust to atmosphere allwaste gas in excess of that required to maintain a predetermined maximumpressure in said tank.

5. In refrigeration apparatus adapted for household use, aninsulated-wall refrigerator structure having therein a container forsolid carbon-dioxide for maintaining a refrigerating temperature bysublimation of said solid carbondioxide, a tank of limited capacitycontaining a liquid to be carbonated and including means for withdrawingliquid as required, a gas conduit leading from said container andcommunicating with said tank to convey Waste carbon-dioxide gas to thetank for carbonating the liquid, and pressure controlling means in saidgas conduit for maintaining the gas at a low pressure sufficient forcarbonating the liquid in said tank for household use, said pressurecontrolling means being disposed to permit escape of excess gas fromsaid conduit to atmosphere exteriorly of said structure so as to relievesaid container of the insulating effect of the gas and permit free heattransfer to the solid carbon-dioxide from the atmosphere within saidstructure.

6. In combination, an insulated refrigerator structure, a container forsolid carbon-dioxide supported in spaced relation within said structureto permit air flow by convection about the container, said containerincluding insulated walls having a heat transfer capacity substantiallyequal to the heat transfer capacity of the walls of said structure formaintaining a balanced temperature within the structure by sublimationof the solid carbon-dioxide, a gas. conduit for conveying wastecarbon-dioxide gas from said container to atmosphere exteriorly of saidstructure and including pressure controlling means for maintaining saidgas at a predetermined pressure, a carbonating tank for liquids, a ductcommunicating at one end with said conduit intermediate said reliefvalve and said container and at its other end with said tank forconducting waste gas to the latter, and a valve in said duct forcontrolling the flow of gas to said tank.

JOHN LI'I'HGOW.

